Travis CI: Parallelize the test matrix

.travis.yml

@@ -4,7 +4,16 @@ language: generic
 sudo: required
 
 env:
-  DOCKER_COMPOSE_VERSION: 1.26.2
+  global:
+    - DOCKER_COMPOSE_VERSION=1.26.2
+    - ANSIBLE_VERSION=2.9.9
+  jobs:
+    - PLATFORM=centos PLAYBOOK=user.yml
+    - PLATFORM=debian PLAYBOOK=user.yml
+    - PLATFORM=ubuntu PLAYBOOK=user.yml
+    - PLATFORM=centos PLAYBOOK=root.yml
+    - PLATFORM=debian PLAYBOOK=root.yml
+    - PLATFORM=ubuntu PLAYBOOK=root.yml
 
 services:
   - docker
@@ -22,24 +31,18 @@ before_install:
   - sudo mv docker-compose /usr/local/bin
 
 install:
-  - sudo pip install ansible==2.9.9 > /dev/null 2>&1
+  - sudo pip install ansible==$ANSIBLE_VERSION > /dev/null 2>&1
 
 script:
   - cd tests
-  - docker-compose up -d
-  - ansible-playbook user.yml -l centos
-  - ansible-playbook user.yml -l debian
-  - ansible-playbook user.yml -l ubuntu
+  - docker-compose config --services | grep $PLATFORM | xargs docker-compose up -d
+  - ansible-playbook $PLAYBOOK -l $PLATFORM
   - docker-compose down
-  - docker-compose up -d
-  - ansible-playbook root.yml -l centos
-  - ansible-playbook root.yml -l debian
-  - ansible-playbook root.yml -l ubuntu
 
 before_cache:
   - >
     mkdir -p $HOME/docker && docker images -a --filter='dangling=false' --format '{{.Repository}}:{{.Tag}} {{.ID}}'
-    | xargs -n 2 -t sh -c 'test -e $HOME/docker/$1.tar.gz || docker save $0 | gzip -2 > $HOME/docker/$1.tar.gz'
+    | xargs -n 2 -t sh -c 'test -e $HOME/docker/$1-$PLATFORM.tar.gz || docker save $0 | gzip -2 > $HOME/docker/$1-$PLATFORM.tar.gz'
 
 notifications:
   webhooks: https://galaxy.ansible.com/api/v1/notifications/